"""文件解析工具

将上传的简历文件（PDF / Word / TXT）转换为纯文本字符串。
PDF 使用 PyMuPDF (fitz) 按文本块提取，保持段落边界和阅读顺序。
"""

import io

import fitz
from docx import Document

from app.core.logger import log


def parse_pdf(content: bytes) -> str:
    """解析 PDF 文件，按文本块提取，过滤图片块，保持阅读顺序"""
    text_parts: list[str] = []
    with fitz.open(stream=content, filetype="pdf") as doc:
        for page in doc:
            for b in page.get_text("blocks", sort=True):
                if b[6] == 0 and b[4].strip():  # type 0=文本块, 1=图片块
                    text_parts.append(b[4].strip())
    return "\n".join(text_parts)


def parse_docx(content: bytes) -> str:
    """解析 Word (.docx) 文件，提取段落和表格文本"""
    try:
        doc = Document(io.BytesIO(content))
    except Exception:
        raise ValueError("无法解析该 Word 文件，如果是旧版 .doc 格式，请另存为 .docx 后重试")
    text_parts: list[str] = []
    for para in doc.paragraphs:
        text = para.text.strip()
        if text:
            text_parts.append(text)
    for table in doc.tables:
        for row in table.rows:
            row_text = "\t".join(cell.text.strip() for cell in row.cells)
            if row_text.strip():
                text_parts.append(row_text)
    return "\n".join(text_parts)


def parse_txt(content: bytes) -> str:
    """解析 TXT 文件，自动检测编码"""
    for encoding in ("utf-8", "gbk", "gb2312", "latin-1"):
        try:
            return content.decode(encoding)
        except (UnicodeDecodeError, LookupError):
            continue
    return content.decode("utf-8", errors="replace")


def parse_to_text(filename: str, content: bytes) -> str:
    """根据文件名后缀自动选择解析方法，返回纯文本"""
    suffix = filename[filename.rfind("."):].lower() if "." in filename else ""
    log.info(f"解析文件: {filename}，类型: {suffix}")
    if suffix == ".pdf":
        return parse_pdf(content)
    elif suffix in (".docx", ".doc"):
        return parse_docx(content)
    elif suffix == ".txt":
        return parse_txt(content)
    else:
        raise ValueError(f"不支持的文件类型: {suffix}，支持: .pdf, .docx, .doc, .txt")